Discarding sabot projectiles

ABSTRACT

A discarding sabot projectile of novel construction is provided whereby separation of the components is accomplished by the combined effect of centrifugal force and the impingement of muzzle gases from the exhausting gun barrel. The sabot preferably comprises a metallic base incorporating means to impart spin to the projectile, and a plastic body firmly surrounding and supporting a sub-caliber core so that the longitudinal axis of the sub-caliber core is coincident with the axis of the full caliber projectile. The plastic body includes a plurality of longitudinally extending slots, or similar weakening lines, beginning at the rear of the plastic body and extending forward toward the tapered nose. Immediately after discharge from the muzzle, the sabot body starts to separate into symmetrical segments, beginning at the rear of the body, under the centrifugal force of projectile spin. The further opening of the body, which progresses along the weakened lines toward the nose, is such that the body segments are struck by the expanding muzzle gas which, in combination with the centrifugal force of spin, effects final separation and dispersal of body components. Projectile separation as described results in minimized muzzle velocity decay and dispersing effects on the sub-caliber core. Exterior configuration of the projectile is uniquely suited for automatic firing in modern, rapid-fire guns under variable environmental conditions.

United States Patent 1 1 Feldmann DISCARDING SABOT PROJECTILES [75]Inventor: Fritz K. Feldmann, Santa Barbara,

211 App]. No.: 854,095

[52] U.S. Cl ..102/93, 102/52 [51] ..F42b 13/16 [58] Field of Search102/52, 93, 94

[56] References Cited UNITED STATES PATENTS 3,435,768 4/1969 Englc..l02/93 X 3,446,147 5/1969 Engle ct a1 102/93 3.496.869 2/1970 Engle102/93 FOREIGN PATENTS OR APPLICATIONS 1,262,830 3/1968 Germany ..l02/93Primary Examiner-Robert F. Stahl Att0rney Patrick J Walsh 57- ABSTRACT Adiscarding sabot projectile of novel construction is [4 1 Feb. 6, 1973provided whereby separation of the components is accomplished by thecombined effect of centrifugal force and the impingement of muzzle gasesfrom the exhausting gun barrel. The sabot preferably comprises ametallic base incorporating means to impart spin to the projectile, anda plastic body firmly surrounding and supporting a sub-caliber core sothat the longitudinal axis of the sub-caliber core is coincident withthe axis of the full caliber projectile. The plastic body includes aplurality of longitudinally extending slots, or similar weakening lines,beginning at the rear of the plastic body and extending forward towardthe tapered nose. immediately after discharge from the muzzle, the sabotbody starts to separate into symmetrical segments, beginning at the rearof the body, under the centrifugal force of projectile spin. The furtheropening of the body, which progresses along the weakened lines towardthe nose, is such that the body segments are struck by the expandingmuzzle gas which, in combination with the centrifugal force of spin,effects final separation and dispersal of body components. Projectileseparation as described results in minimized muzzle velocity decay anddispersing effects on the sub-caliber core. Exterior configuration ofthe projectile is uniquely suited for automatic firing in modern,rapid-fire guns under variable environmental conditions.

7 Claims, 9 Drawing Figures PATENTEDFEB 6 I975 3.714.900 SHEET 10F 3 7 vIWZL PAIENIEDFEB 6 I975 3. 714,900 SHEET 2 BF 3 INVENTOR ATTORNEYSPATENTEDFEB 6 I973 3.714.900

SHEET 30F 3 INVENTOR ATTORNEY5 DISCARDING SABOT PROJECTILES Thisinvention relates to projectiles for guns and rifles and, moreparticularly, to discarding sabot projectiles incorporating asub-caliber core.

It has long been known that because of superior intermediate andterminal ballistic velocities and resulting increase in performance, asub-caliber core discharged from a full caliber gun or rifle canpenetrate and defeat heavier, or more resistant, targets than isnormally possible with armor piercing ammunition of full caliber.Accordingly, considerable efforts have been devoted in the past to thedevelopment of a variety of types of discarding sabots to serve as thelaunching means for such sub-caliber cores. While in many instancessuperior penetration performances have been realized to some extent, thediscarding sabot projectiles heretofore known have not been completelysatisfactory. These projectiles have shown inherent disadvantages whicheither retarded the realization of their full armor penetratingpotential, or which induced or accentuated other undesirablecharacteristics, which do not ordinarily materially affect theperformance of conventional full caliber projectiles. These lattercharacteristics have included (a) reduced hitting accuracy due tonon-axial, dispersing forces and moments influencing the sub-calibercore during separation from the sabot components; (b) deterioration inperformance and reliability under adverse environmental conditions,particularly at extreme temperature conditions; (c) limited usefulnessdue to non-compatibility with the feeding and loading mechanism inconventional automatic guns and rifles; (d) added danger to friendlytroups due to excessive zones of dispersal of the rapidly moving sabotcomponents; and (e) increased production costs, attributable primarilyto the requirements for exceedingly close manufacturing tolerances andthe added materials and fabrication costs.

To illustrate some of the foregoing disadvantages,

one such known prior discarding projectile accomplishes separation ofthe sabot and the sub-caliber core by differential drag forces betweenthe former and the latter. This full caliber sabot is essentially cupshaped, having an axial bore in its forward portion, and receives thebase and a considerable portion of the body of the sub-caliber coresnugly within this bore. When the projectile is fired, the largerdiameter of the sabot is accelerated by the gases generated and carriesthe sub caliber projectile to an excellent muzzle velocity. After exitfrom the muzzle of the gun, greater aerodynamic drag forces act on thelarger sabot than on the smaller sub-caliber core, thus causing relativeaxial sliding movement between the core and the sabot, untii separationis achieved. if the fit between the sabot and the core is relativelytight, then, obviously, additional drag forces will be transmitted byfriction from the sabot to the core, thus reducing the velocity of thecore to an undesirable degree and materially defeating the primarypurpose of the sabot. On the other hand, if the fit is relatively loose,the rotating sabot will not impart the proper rotation to the core,and/or the core will not be properly axially aligned, thus contributingto poor hitting accuracy of the core at the target. Considering thesefactors, it is apparent that a very high degree of accuracy ofmachining, and very close tolerances, is

required in such a projectile to insure acceptable performance.Nevertheless, because the core is usually desirably of a very heavy,dense metal while the sabot parts are desirably of lighter, less denseand more inexpensive materials, it is similarly apparent that despitethe finest workmanship and the closest tolerances, the differentcoefficients of expansion of such different materials inevitably meanthat the closeness of the fit will vary widely under differenttemperature and other environmental conditions. it will thus be readilyunderstood that while such a projectile might perform acceptably attemperatures of F., at subfreezing or elevated temperatures, the fit maybe too close or too loose to permit proper performance. On the one hand,increased tolerances tend to increase the core dispersion and reducehitting accuracy. On the other hand, decreased tolerances give rise to adetrimental projectile deceleration which is largely self-defeating. Asa result, the projectile accuracy and penetration performance over thedesired operational temperature range of from -65F to l25F, variesconsiderably.

To overcome the many objections and disadvantages of the above-mentionedtype of projectile, it has also previously been proposed to accomplishseparation of the sub-caliber core from the sabot components through thecombination of aerodynamic and centrifugal forces, the latter producedby the normal spin injected to the projectile while moving through thegun barrel. In a typical projectile of this type, the sabot componentsradially surrounding the sub-caliber core are in the form of petalswhich separate radially from the core after exit from the muzzle underthe combined action of the centrifugal forces just mentioned and theretarding aerodynamic action of the surrounding atmosphere. For example,it has.been proposed that the leading edges-of each petal have anaxially inclined surface which catches in the air stream and propels theleading edge of the petal outwardly away from the core. it has beendetermined, however, that separation of this type of projectile tends tointroduce dispersions and undesirable projectile deceleration, and thus,this projectile is also subject to some of the disadvantages discussedpreviously in detail. In addition, many such projectiles suffer theadditional disadvantage that they are not readily adaptable to the rapidor automatic firing of which modern conventional weapons are capable.

Accordingly, it is an object of the present invention to provide aprojectile sabot assembly which overcomes to a degree heretoforeunrealized, the disadvantages of prior sabot projectiles, providingpenetration performance greatly superior to conventional armor piercingprojectiles.

it is a further object of this invention to provide an efficient andeffective sub-caliber armor piercing projectile adaptable for single orautomatic firing from conventional guns and artillery.

It is a further ofject of this invention to provide a sabot projectilewherein the separation of the subcaliber core from the full-calibercomponents results in minimum launch dispersion without inducing asignificant velocity decay to the sub-caliber core, other than thenormal aerodynamic drag forces acting on the core.

It is a still further object of this invention to provide a novel spinstabilized, discarding sabot projectile of improved effectiveness, whichprojectile is easily manufactured, and is readily adaptable to use inconventional weapons under a wide variety of environmental conditionsand loads, without substantial variation in performance.

To accomplish these and other objects of the present invention, Iprovide a novel sabot projectile assembly characterized by itsrelatively uncomplicated construction, its adaptability to use inexisting single or automatic fire guns, and its adaptability toseparation under the combined effects of centrifugal force and the forceof impingement of the gases exiting from the muzzle, to effect a morerapid and efficient separation of the sabot components, thus maintainingmaximum hitting accuracy and minimum deceleration of the sub-calibercore in flight.

A more complete understanding of the invention and of the variousembodiments which the invention may take, may be gained from thefollowing illustrative examples, and from the accompanying drawings inwhich;

FIG. I is a side elevational view of one projectile embodying theelements of the present invention.

FIG. 2 is a longitudinal sectional view, also an elevation taken alongline 2-2 of FIG. 1.

FIG. 3 is a vertical cross-sectional view of the projectile of FIGS. 1and 2 taken along line 3-3 of FIG. 2.

FIG. 4 is a further longitudinal view of the projectile of FIGS. 1 and2, illustrating the initiation of separation of the projectilecomponents as the projectile exits from a gun barrel.

FIG. 5 is a further longitudinal view illustrating only schematicallythe further dispersal of the projectile components.

FIG. 6 is another side elevational view showing a modified projectileaccording to this invention.

FIG. 7 is a side elevational view of another projectile, modified fromthat of FIG. 1, within the scope of the present invention.

FIG. 8 is a longitudinal sectional view, also in elevation, taken alongline 8-8 of FIG. 7.

FIG. 9 is a vertical sectional view of the projectile of FIGS. 7 and 8taken along line 9-9 of FIG. 8.

As shown generally in FIG. 1, a full-caliber projectile according to thepresent invention may have an outward shape and symmetry very similar tothose of conventional projectiles, providing an advantage not heretoforeobtained with most prior discarding sabot projectiles. It will be noted,however, that while the shape of this projectile is generallyconventional, dis similarities to conventional projectiles are alsoreadily apparent. Major components or parts of this new projectileinclude: the sabot base (generally indicated by the numeral 10), whichmay be made of some light metal such as aluminum; a circular ring 12extending circumferentially about a portion of the sabot base andpreferably formed of a soft metal or a suitable plastic; the sabot body,generally indicated by the numeral 14, which may be formed of variousmaterials but is preferably formed from a plastic having relativetoughness and heat resistance; and the sub-caliber core 16 (see FIG. 2),which desirably is formed ofa relatively heavy, dense metal. In theembodiment shown in FIG. I, the sabot body is composed of twosubsections, the cylindrical body 20 and the tapering nose shield 24,attached to the forward end of the cylindrical subsection.

As shown more particularly in FIG. 2 of the drawings, the sabot base 10has a concave rearward face 30 which provides an enlarged surfaceagainst which the propelling gases may thrust. The precise shape anddimensions of this face 30 may vary, although preferably it should havethe somewhat conical shape illustrated in FIG. 2. The sabot base 10 alsopreferably includes a forward member 32 providing a seat 34 for the baseof the sub-caliber core 16. The member 32 also includes an enlargedannular portion 36 rearward of the seating surface, for reasons whichwill be hereinafter explained. Although the base of the sub-caliber coreis intended to abut against the seat 34, the core is primarily enclosedwithin the annular bore of cylindrical sub-section 20. The plastic wallthus defined in the cylindrical section 20 is substantially uniform inthickness and firmly encloses the subcaliber core 16 and supports it sothat the longitudinal axis of the core is aligned with the rotationalaxis of the full-caliber projectile. Preferably the forward interiorsurface 26 of the body portion is necked or tapered slightly, toapproximately the same angle as the corresponding nose portion of thesub-caliber projectile, so that the section 20 firmly restrains the core16 both from lateral movements and from forward movement beyond apre-determined limit. The nose portion of the sub-caliber core extendingthrough and beyond the cylindrical body wall 20 is enclosed andprotected by the nose shield 24, which is attached to the forward end ofthe cylindrical body by means of mating threaded portions 40 and 42.

It will be noted from FIG. 3 that the cylindrical body wall 20, shown invertical cross-section, comprises a plurality of wall segments 22.Although, as shown in FIGS. 1, 2 and 3, these segments are four innumber, the invention also contemplates that the cylindrical section mayhave any number of segments, five or six,

for example, subject to the conditions hereinafter set forth. Thesegments 22 are substantially symmetrical and are separated bylongitudinal slots 28 which extend from the rear end of the cylindrical20 body forward, over most of its entire length, terminating short ofthe forward most portion of the body. The purpose of the slots 28 is toprovide weakened lines of separation of the body wall so that, under theinfluence of outwardly directed radial forces, the wall 20 willautomatically split into the symmetrical segments 22. Further, the slotsterminate at a forward point so that unweakened forward portion of thebody 20 will offer greater resistance to fracture under radial stressesthan the rearward body portions. In the examples shown, the slots 28extend through the entire thickness of the body wall, although, aspointed out hereinafter, modifications of the depth of the cut arepermissible. It should be further noted that the rear end of the body 20is also notched or reduced slightly in diameter to receive a thinretaining ring 44 substantially flush with the exterior surface. Theinterior surface of the section 20 is provided with an annularrecess 38adapted to receive the enlarged annular base portion 36. The sabotprojectile is thus conveniently assembled by placing a sub-caliber corewithin the body 14, attaching the body to the base 30 by flexing thesegments 22 apart and bringing the base and body together until theenlarged base 36 aligns with the recess 38 and the elastic segments snapinto place about the base portion 32, as shown in FIG.

2. The retaining ring 44 is applied to lock the aft ends of the segmentsinto place to prevent separation during subsequent handling and loadingof the projectile.

The nose section 24, as mentioned above, encloses the forward portion ofthe sub-caliber core 16 and it is preferable that the nose be tapered,similar to conventional projectiles, so that its exterior contours willassure compatibility with the loading and firing mechanisms of standardguns. The interior configuration of the nose section is not critical solong as it provides adequate room and protection for the forward portionof the sub-caliber core 16. In the embodiment of FIGS. 1-3, longitudinalgrooves 46 are also symmetrically spaced around the base of the noseshield 24, preferably equal in number to the slots 28 in the bodyportion 20. The function of these grooves 46 is to assist in symmetricalseparation and dispersal of the nose shield.

The projectile of this invention, and as described above, may becombined with a powder-containing cartridge of conventional type, orotherwise adapted for firing from a gun or rifle as desired. In theembodiments. shown, the projectile is adapted for firing from a barrelhaving conventional helical rifling. However, other known means forachieving spin stabilization of the projectile in flight may be employedif desired.

The process of separation of the various sabot components after firing,demonstrating some of the objectives of the invention, generallyproceeds according to the following sequence: At the instant of firing,the projectile accelerates into the gun barrel, the slightly largercircular band 12 thus contacting the rifling in the barrel and effectingobturation as the projectile continues to move forward under thepressure of expanding gases. The ring 12, in addition to preventingby-pass of gases, turns with the rifling and thereby imparts spin to thesabot base and, hence, to the other sabot components. It may be notedthat the spin moment is imparted to the sub-caliber core because of thestrong friction forces at the interface of the seat 34 and the core 16,generated by the great acceleration of the projectile. If desired, theresistance to slippage at the interface may be increased, and full spinassured, by providing a small sharp-edged groove or series of grooves inthe base of the sub-caliber core. During initial acceleration, thesofter metal of the sabot base will be swaged or pressed into suchgrooves, thus increasing transfer of torque between the base 10 and thecore 16.

As the projectile accelerates through the length of the barrel, the spinimparted creates substantial centrifugal forces which tend to move thewall segments 22 radially with respect to the longitudinal axis of theprojectile. These forces however, are resisted by the surrounding wallsof the gun barrel and thus substantial equilibrium is maintained whilethe projectile is within the barrel. Upon exit of the sabot body fromthe barrel, however, resistance to the-centrifugal forces of rotation issuddenly diminished. As shown in FIG. 4, the rearward portions of wallsegments 22 offer the least resistance and tend to move outwardradially, exerting great tensile force on the thin restraining band 44.The band 44 ruptures and separation of the sabot body components isinitiated by the outward flexing of the aft portions of the segments 22,while the forward ends are still restrained by the unslotted portion ofthe cylindrical body 20.

As the sabot base 10 continues to move forward and clears the muzzleexit, the high pressure gases within the barrel expand and are releasedto the atmosphere causing a strong stream of gas which is stillaccelerating. These accelerating gases actually overtake the projectileand impinge on the aft ends of the partially separated segments 22. Thisgas impingement augments the action of the centrifugal force alreadyacting on the segments and assists in the further separation of the bodycomponents. It should be noted that this gas impingement has a forwardcomponent which may offset to some extent the aerocynamic drag forcesalready tending to slow the projectile. As a certain opening angle ofthe segments 22 is achieved, the combined forces cause fracture of theunslotted portion of the cylindrical sabot and the wall segments arediscarded in a radial direction simultaneously with the fracturing ofthe body portion 20. The nose 24 is likewise fractured intosubstantially symmetrical segments defined by the grooves 46. Thesesegments 48 are of low density and thus are decelerated very rapidly,presenting minimum danger to friendly troups. Although impingement ofthe muzzle gases significantly affects and improved the separation anddispersal of the body components of this projectile, due to the novelconstruction described, the sub-caliber core 16 itself is substantiallyprotected from any adverse dispersing effect of the muzzle gases by thesabot base 10 which proceeds along the line of tire behind the core.

Following separation of the sabot body, aerodynamic drag forces rapidlydecelerate the full caliber sabot base 10, which then falls far short ofthe target. The sub-caliber core-16, unrestrained and unhampered by theradial separation of other components, then proceeds along the line offire to the target with minimum loss of velocity and minimum dispersion.It

should be especially noted that separation of the core and base takesplace without transfer of decelerating forces from the base to the core.FIG. 5 is a schematic representation showing the completely separatedcomponents, but it should be understood that the illustration, ofnecessity, does not show the parts in the actual spatial relationshipsthat occur during the actual discarding process.

The separation of the sabot as described above normally occurssimultaneously upon leaving the gun barrel. It will be understood fromthe above description that the separation of the components under theinfluence of spin induced centrifugal force and the impingement ofmuzzle gases reduces to a minimum the velocity decay in the sub-caliberprojectile due to transfer of decelerating and dispersing forces fromthe full-caliber components prior to complete separation of the latterfrom the sub-caliber core. In addition, the elimination of slidingsurfaces between the core and other components holds friction forces,another major cause of velocity decay to a minimum and, further, therequirement for close machining tolerances is eliminated. Moreover, itwill be seen that the method of separation provides minimum transverseeffects on the sub-caliber core during separation and thus promotesimproved hitting accuracy.

In another embodiment of the present invention illustrated in FIG. 6,the wall segments 52 of the sabot body 14 may have serrated interfaces54 which interfit as shown, in lieu of the straight longitudinal slots28.

The generally longitudinally extending serrated interfaces permitseparation of the wall segments in the manner previously described, butthe serrations permit the transmission of shear forces between thesegments and thus increase the structural rigidity of the cylindri calbody 20. This is a desirable advantage when the projectile may besubjected to substantial environmental shocks and loads, as in the caseof automatic guns having extremely high rates of fire or guns havingvery high muzzle velocities. The serrated interfaces 54 also providesomewhat improved protection of the subcaliber core 16 against otherenvironmental conditions such as humidity, salt spray, dust, and thelike.

FIGS. 7 and 8 illustrate a variety of modifications that can be made tothe projectile of FIGS. 1-3, as may be desired according to convenienceof manufacture, type of gun employed, the performance desired, or otherrequirements. It will be noted first that the sabot body 14 of FIGS. 7and 8 is integrally formed, rather than comprising two separate sectionsas in the embodiment of FIG. 1. Further, it will be noted that the body14 may be secured to the sabot base 10 by means of mating screw-threadedportions 66, 68 in the base and body respectively, rather than theretainer ring and assembly illustrated in FIGS. 1-3.

It will also be seen that rather than the full-depth longidutinal slots28 or serrated interfaces 34, longitudinal cuts or grooves 64 ofsubstantial depth may be made into the outer wall of the body 14 to formweakening lines which, upon rupture, divide the wall into substantiallysymmetrical segments 62, which otherwise are similar in function andoperation to the segments 22. Preferably the grooves 64 are V-shaped andextend only partially into the wall of the sabot body, as shown moreclearly in FIGS. 8 and 9. This partial grooving, in contrast to the fullslotting shown in FIGS. 1 and 2, serves to increase the structuralrigidity of the projectile. It further results in the additionaladvantage that the sub-caliber projectile is completely enclosed, thusprotecting it from certain adverse environmental conditions. The depthof the V-shaped groove may vary de' pending on the strength of thematerial used, so as to assure the breakage of the sabot wall alonglongitudinal lines in these areas under the influence of the specificcentrifugal force that is applied to the projectile at the selectedconditions of muzzle velocity and spin.

Further, it will be observed that the cuts or grooves 64 are formed sothat the body wall is weakest, and therefore most susceptible torupture, at the aft end and is strongest and least susceptible torupture at the forwardmost end, so that separation under the centrifugalforces of spin will initiate at the rear of the body and progressforward toward the nose of the body 14. To insure initial rupture at theaft end, it may be desirable to vary the depth of the cut or groove 64,depending upon the strength characteristics of the particular materialutilized, making the groove deeper at the aft end and progressivelyshallower toward the forward end.

As noted earlier, good projectile hitting accuracy of the projectilerequires substantial co-axial alignment of the barrel axis, the sabotprojectile axis, and the axis of the sub-caliber core. Apart from thiscondition, however, only a light press fit is desired between the sabotassembly and the sub-caliber core, and the machining tolerances betweenthe sabot base and the contacting surfaces of the core are neither closenor critical.

A further modification illustrated in FIG. 8 is the provision of a smallcircular hole through the bottom of the sabot base, providingcommunication between the rear face 30 of the'sabot base and the base ofthe sub-caliber projectile 16. Such an opening is useful when it isdesired to fire tracer projectiles. The opening provides access so thatthe burning propellant gases may ignite the tracer material at the rearof the sub-caliber projectile.

It may be further observed that the seat for the aft end of thesubcaliber core may be recessed into the sabot base 10 so long as careis taken to avoid signifi cant frictional contact between the sides ofsuch recess and the core. For example, in the embodiment shown in FIG.8, the seat 72 is within an annular bore 74 provided in the forwardportion of the sabot base 10. It is particularly important, however,that the bore 74 be of greater diameter than the base of the core 16, sothat a loose fit is provided, and separation of the core and the basewill not transmit deceleration forces to the core through slidingfriction.

With any or all of the modifications described, the basic principle ofsabot separation is maintained generally as described above. Forexample, in a projectile constructed as shown in FIGS. 7 and 8separation initiates immediately upon exit of the sabot body 14 from thegun barrel. Separation of the body 14 begins at the aft end, in thevicinity of the threated region, and

progresses, as before, along the grooves 64 toward the nose. When thesegments 62 have been partially opened by the centrifugal force of spinthe aft ends of the segments are struck by the exhausting muzzle gasthus efi'ecting complete separation and radial dispersion. Optimumdispersion is achieved when the segments, including the nose separate assymmetrically as possible, and therefore it is highly desirable that theprojectile for a given application be designed to effectuate thisobjective.

It is, of course, possible to contemplate still further modificationsand uses for the projectile herein disclosed. For example, rather than asolid sub-caliber core of high density, one may utilize the samediscarding sabot principle in connection with other types of projectilessuch as high explosives, single flechette, multiple flechette, or thelike.

Accordingly, in view of the wide applicability of the principles hereindisclosed, I do not wish to be limited to the particular designs andembodiment herein disclosed. It therefore should be understood thatother adaptations of my invention are intended to be comprehended withinthe meaning and range of the following claims.

What is claimed is:

l. A spin stabilized discarding sabot projectile adapted for firing fromthe muzzle of a gun comprising a sub-caliber core, a full-caliber basehaving a member for receiving the core, means mounted on said base toimpart rotation to the projectile during traverse of a gun barrel, asabot covering the sub-caliber core, said sabot having a forward bodyportion for covering the forward portion of the core, a plurality ofbody segments secured to the forward body portion and extendingrearwardly from the forward body portion in covering relationship to thecore, the body segments engaging and being secured to the base, saidbody segments being defined by areas of weakness extendinglongitudinally of the sabot, first means for holding the forward portionof the body segments in fixed relation to each other as the projectilespins when fired, second means for holding the rear portion of the bodysegments in fixed relation to each other, said second means forreleasing the rear portion of said body segments for separation andexposure to propelling gases issuing from the gun muzzle uponapplication of centrifugal force to the projectile so that the sabot isremoved from the projectile by a combination of centrifugal forceimparted to the projectile and the force of propelling gases issuingfrom a gun barrel and impinging on the rearwardly opened body segmentsto remove the sabot from the sub-caliber core.

2. A spin stabilized discarding sabot projectile adapted for firing fromthe muzzle of a gun comprising a sub-caliber core, a full-caliber sabotbase having means for receiving the core and means for receiving a sabotbody, a sabot body, means for securing the sabot body in fixed relationto the base and in covering relation to the core, said sabot body havinga forward body portion and a plurality of body segments connected to andextending rearwardly from the forward body portion in coveringrelationship to the core to define a rear body portion, said bodysegments being defined by radially spaced slots extending longitudinallyof the sabot body, rupturable means for retaining the body segments infixed relation to each other, said rupturable means for fracturing onthe application of centrifugal force to the projectile, and saidrupturable means for further fracturing initially at the rear bodysegment portion of the sabot body with the fracture progressing towardthe forward body portion so that the sabot body is removed from theprojectile by the action of centrifugal force imparted to the projectileand by the force of propelling gases issuing from the gun barrel.

3. A spin stabilized discarding sabot projectile adapted for firing fromthe muzzle of a gun comprising a sub-caliber core, a full-caliber sabotbase having means for receiving the core, means to impart rotation tothe projectile during traverse of a gun barrel, a sabot body coveringthe subcaliber core, means for retaining the sabot body on the bass incovering relation to the core, said sabot body having a forward bodyportion, a plurality of body segments secured to and extendingrearwardly from the forward body portion in covering relationship to thecore, said body segments being defined by recesses extendinglongitudinally of the sabot body, means for securing the body segmentsin fixed relation to each other along said recesses, said securing meansfor fracturing on the application of centrifugal force to the projectileso that the body segments separate initially at the rear portion of thesabot body and said body segments for further separating progressivelytoward the forward body portion so that the separated body segments areexposed to the force of propelling gases issuing from a gun barrel whichgases impinge upon the body segments to discard the sabot body from thesub-caliber core.

4. A spin stabilized discarding sabot projectile adapted for firing fromthe muzzle of a gun comprising a sub-caliber core, a full-caliber sabotbase having a recess therein for receiving the core, means on said sabotbase for imparting rotation to the projectile during traverse of a gunbarrel, a sabot body for covering the sub-caliber core, means forsecuring the sabot body to the base in covering relation to the core,the sabot body having an inner surface adapted to engage and retain thecore for rotation at substantially the speed of projectile rotation,said sabot body having a forward body portion and a plurality of bodysegments extending rearwardly from the forward body portion in coveringrelationship to the core, said body segments being defined by weakenedareas extending longitudinally of the sabot body, rupturable means forretaining the body segments in fixed relation to each other, saidrupturable means for fracturing on the application of centrifugal forceto the projectile so that the sabot body ruptures first at its rearportion while the body segments are retained by the forward body portionso that the sabot body is separated from the projectile by the action ofcentrifugal force which separates and exposes the body segments and bythe action of propelling gases issuing from the gun muzzle which impingeon and move the separated sabot body away from the subcaliber core.

5. A discarding sabot projectile adapted for firing from the muzzle of agun comprising a sub-caliber core, having a conical front body portionand a generally cylindrical rear body portion, a sabot base having arecess for receiving said core, a sabot body secured to the base incovering relation to the core, said sabot body having an interior recesswith an interior surface adapted to engage the front body portion of thecore for positioning the core in axial alignment within the projectile,said sabot body having a forward body portion, a rear body portionconnected to and extending rearwardly from said forward body portion ofthe sabot, means for imparting rotation to said projectile duringtraverse of a gun barrel, said rear body portion having'means forfracturing initially at the rear portion of said sabot body and forfurther fracturing progressively toward the forward body portion forcomplete fracture of the sabot while under the influence of centrifugalforce said fractured sabot for moving radially away from the core sothat the sabot body is removed from the projectile by said centrifugalforce and by the force of propulsion gases impinging on the sabot, andsaid sabot base is removed from the core by aerodynamic drag forces.

6. in a spin stabilized discarding sabot projectile having asubstantially full-caliber base and a sub-caliber core fitted into arecess in the base, the improvement which comprises a full-caliber sabotbody having means for connection to the base in covering relationship tothe sub-caliber core, the sabot body having a forward body portion and aplurality of body segments connected to and extending rearwardly fromthe forward body portion in a longitudinal direction and in coveringrelation to the sub-caliber core, said body segments being defined byrecesses between adjacent body segments extending longitudinally of thesabot, means for retaining the body segments together, said retainingmeans for fracturing under the influence of centrifugal force as theprojectile spins and for releasing the body segments for separatingradially from the core first at the rear portion and for furtherseparating radially progressively toward the forward body portion sothat the gases issuing from the muzzle during firing impinge upon therearwardly opened segments to discard the sabot body from theprojectile.

7. A round of ammunition having a spin stabilized discarding sabotprojectile comprising the combination of a powder-containing cartridge,a full-caliber sabot base secured to cartridge in position to beseparated from the cartridge upon firing the round, sub-caliber core,means mounted on the base to impart rotation to the projectile duringtraverse of a gun barrel, a sabot body retained by the base for coveringthe sub-caliber core, said sabot body having a forward body portion anda plurality of body segments extending rearwardly from the forward bodyportion in covering relationship to the core, said body segments beingdefined by recesses extending longitudinally of the sabot body, meansfor holding the body segments in fixed relation to each other, saidholding means to release under the influence of centrifugal force as theprojectile rotates so that the rearwardly extending body segmentsseparate radially from the rear portion of the core while beingrestrained the forward body portion so that the sabot body is removedfrom the projectile by the action of centrifugal force imparted to thesabot and the force of exhaust propelling gases issuing from a gunbarrel which gases cooperate with the separated body segments to removethe sabot body from the sub-caliber core, and so that the sabot base isexposed to aerodynamic drag forces for removing the base from the core.

v FORM PO-IOSO (IO-69) UNI'BED STATES PA'WENT OFFM IF. C E R'EI H (.1 ATE11 Mi CU RR WIT HUN Patent No. 3 714 ,90 Q Dated l" oLu qr It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 5, line 21, after "cartridge" should read 31 FIG. 2 Column 9,line 44, "bass'Vshould read base Signed and sealed this 4th day ofDecember 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents USCOMM-DC 60376-P69 b u.s. covznmnam PRINTINGOFFICE: 1969 o-3ee-s:u.

1. A spin stabilized discarding sabot projectile adapted for firing fromthe muzzle of a gun comprising a sub-caliber core, a full-caliber basehaving a member for receiving the core, means mounted on said base toimpart rotation to the projectile during traverse of a gun barrel, asabot covering the sub-caliber core, said sabot having a forward bodyportion for covering the forward portion of the core, a plurality ofbody segments secured to the forward body portion and extendingrearwardly from the forward body portion in covering relationship to thecore, the body segments engaging and being secured to the base, saidbody segments being defined by areas of weakness extendinglongitudinally of the sabot, first means for holding the forward portionof the body segments in fixed relation to each other as the projectilespins when fired, second means for holding the rear portion of the bodysegments in fixed relation to each other, said second means forreleasing the rear portion of said body segments for separation andexposure to propelling gases issuing from the gun muzzle uponapplication of centrifugal force to the projectile so that the sabot isremoved from the projectile by a combination of centrifugal forceimparted to the projectile and the force of propelling gases issuingfrom a gun barrel and impinging on the rearwardly opened body segmentsto remove the sabot from the sub-caliber core.
 1. A spin stabilizeddiscarding sabot projectile adapted for firing from the muzzle of a guncomprising a sub-caliber core, a full-caliber base having a member forreceiving the core, means mounted on said base to impart rotation to theprojectile during traverse of a gun barrel, a sabot covering thesub-caliber core, said sabot having a forward body portion for coveringthe forward portion of the core, a plurality of body segments secured tothe forward body portion and extending rearwardly from the forward bodyportion in covering relationship to the core, the body segments engagingand being secured to the base, said body segments being defined by areasof weakness extending longitudinally of the sabot, first means forholding the forward portion of the body segments in fixed relation toeach other as the projectile spins when fired, second means for holdingthe rear portion of the body segments in fixed relation to each other,said second means for releasing the rear portion of said body segmentsfor separation and exposure to propelling gases issuing from the gunmuzzle upon application of centrifugal force to the projectile so thatthe sabot is removed from the projectile by a combination of centrifugalforce imparted to the projectile and the force of propelling gasesissuing from a gun barrel and impinging on the rearwardly opened bodysegments to remove the sabot from the sub-caliber core.
 2. A spinstabilized discarding sabot projectile adapted for firing from themuzzle of a gun comprising a sub-caliber core, a full-caliber sabot basehaving means for receiving the core and means for receiving a sabotbody, a sabot body, means for securing the sabot body in fixed relationto the base and in covering relation to the core, said sabot body havinga forward body portion and a plurality of body segments connected to andextending rearwardly from the forward body portion in coveringrelationship to the core to define a rear body portion, said bodysegments being defined by radially spaced slots extending longitudinallyof the sabot body, rupturable means for retaining the body segments infixed relation to each other, said rupturable means for fracturing onthe application of centrifugal force to the projectile, and saidrupturable means for further fracturing initially at the rear bodysegment portion of the sabot body with the fracture progressing towardthe forward body portion so that the sabot body is removed from theprojectile by the action of centrifugal force imparted to the projectileand by the force of propelling gases issuing from the gun barrel.
 3. Aspin stabilized discarding sabot projectile adapted for firing from themuzzle of a gun comprising a sub-caliber core, a full-caliber sabot basehaving means for receiving the core, means to impart rotation to theprojectile during traverse of a gun barrel, a sabot body covering thesubcaliber core, means for retaining the sabot body on the bass incovering relation to the core, said sabot body having a forward bodyportion, a plurality of body segments secured to and extendingrearwardly from the forward body portion in coveriNg relationship to thecore, said body segments being defined by recesses extendinglongitudinally of the sabot body, means for securing the body segmentsin fixed relation to each other along said recesses, said securing meansfor fracturing on the application of centrifugal force to the projectileso that the body segments separate initially at the rear portion of thesabot body and said body segments for further separating progressivelytoward the forward body portion so that the separated body segments areexposed to the force of propelling gases issuing from a gun barrel whichgases impinge upon the body segments to discard the sabot body from thesub-caliber core.
 4. A spin stabilized discarding sabot projectileadapted for firing from the muzzle of a gun comprising a sub-calibercore, a full-caliber sabot base having a recess therein for receivingthe core, means on said sabot base for imparting rotation to theprojectile during traverse of a gun barrel, a sabot body for coveringthe sub-caliber core, means for securing the sabot body to the base incovering relation to the core, the sabot body having an inner surfaceadapted to engage and retain the core for rotation at substantially thespeed of projectile rotation, said sabot body having a forward bodyportion and a plurality of body segments extending rearwardly from theforward body portion in covering relationship to the core, said bodysegments being defined by weakened areas extending longitudinally of thesabot body, rupturable means for retaining the body segments in fixedrelation to each other, said rupturable means for fracturing on theapplication of centrifugal force to the projectile so that the sabotbody ruptures first at its rear portion while the body segments areretained by the forward body portion so that the sabot body is separatedfrom the projectile by the action of centrifugal force which separatesand exposes the body segments and by the action of propelling gasesissuing from the gun muzzle which impinge on and move the separatedsabot body away from the sub-caliber core.
 5. A discarding sabotprojectile adapted for firing from the muzzle of a gun comprising asub-caliber core, having a conical front body portion and a generallycylindrical rear body portion, a sabot base having a recess forreceiving said core, a sabot body secured to the base in coveringrelation to the core, said sabot body having an interior recess with aninterior surface adapted to engage the front body portion of the corefor positioning the core in axial alignment within the projectile, saidsabot body having a forward body portion, a rear body portion connectedto and extending rearwardly from said forward body portion of the sabot,means for imparting rotation to said projectile during traverse of a gunbarrel, said rear body portion having means for fracturing initially atthe rear portion of said sabot body and for further fracturingprogressively toward the forward body portion for complete fracture ofthe sabot while under the influence of centrifugal force said fracturedsabot for moving radially away from the core so that the sabot body isremoved from the projectile by said centrifugal force and by the forceof propulsion gases impinging on the sabot, and said sabot base isremoved from the core by aerodynamic drag forces.
 6. In a spinstabilized discarding sabot projectile having a substantiallyfull-caliber base and a sub-caliber core fitted into a recess in thebase, the improvement which comprises a full-caliber sabot body havingmeans for connection to the base in covering relationship to thesub-caliber core, the sabot body having a forward body portion and aplurality of body segments connected to and extending rearwardly fromthe forward body portion in a longitudinal direction and in coveringrelation to the sub-caliber core, said body segments being defined byrecesses between adjacent body segments extending longitudinally of thesabot, means for retaining the body segments together, saId retainingmeans for fracturing under the influence of centrifugal force as theprojectile spins and for releasing the body segments for separatingradially from the core first at the rear portion and for furtherseparating radially progressively toward the forward body portion sothat the gases issuing from the muzzle during firing impinge upon therearwardly opened segments to discard the sabot body from theprojectile.